title: Radiation dose of CT coronary angiography in clinical practice: objective evaluation of strategies for dose optimization.
abstract: BACKGROUND
  CT coronary angiography (CTCA) is an evolving modality for the diagnosis of coronary artery disease. Radiation burden associated with CTCA has been a major concern in the wider application of this technique. It is important to reduce the radiation dose without compromising the image quality.
  
  
  OBJECTIVE
  To estimate the radiation dose of CTCA in clinical practice and evaluate the effect of dose-saving algorithms on radiation dose and image quality.
  
  
  METHODS
  Effective radiation dose was measured from the dose-length product in 616 consecutive patients (mean age 58 ± 12 years; 70% males) who underwent clinically indicated CTCA at our institution over 1 year. Image quality was assessed subjectively using a 4-point scale and objectively by measuring the signal- and contrast-to-noise ratios in the coronary arteries. Multivariate linear regression analysis was used to identify factors independently associated with radiation dose.
  
  
  RESULTS
  Mean effective radiation dose of CTCA was 6.6 ± 3.3 mSv. Radiation dose was significantly reduced by dose saving algorithms such as 100 kV imaging (-47%; 95% CI, -44% to -50%), prospective gating (-35%; 95% CI, -29% to -40%) and ECG controlled tube current modulation (-23%; 95% CI, -9% to -34%). None of the dose saving algorithms were associated with a significant reduction in mean image quality or the frequency of diagnostic scans (P = non-significant for all comparisons).
  
  
  CONCLUSIONS
  Careful application of radiation-dose saving algorithms in appropriately selected patients can reduce the radiation burden of CTCA significantly, without compromising the image quality.
authors.affiliation: Clinical Imaging and Research Centre, Wellington Hospital, London NW8 9LE, UK. dryerramasu@yahoo.com
authors.forename: Ajay
authors.initials: A
authors.lastname: Yerramasu
authors.forename: Shreenidhi
authors.initials: S
authors.lastname: Venuraju
authors.forename: Satvir
authors.initials: S
authors.lastname: Atwal
authors.forename: Dennis
authors.initials: D
authors.lastname: Goodman
authors.forename: David
authors.initials: D
authors.lastname: Lipkin
authors.forename: Avijit
authors.initials: A
authors.lastname: Lahiri
mesh_terms: D000465:Algorithms; D055424:Cardiac-Gated Imaging Techniques; D003287:Contrast Media; D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D059629:Signal-To-Noise Ratio; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media